Surgical cutting and fastening instrument having a control system

ABSTRACT

A surgical instrument assembly comprising a cartridge jaw, a cartridge positioned in the cartridge jaw, staples removably stored in the cartridge, a drive screw extending within the cartridge iaw, a firing member operably engaged with the drive screw, an anvil iaw, an electric motor configured to rotate the drive screw, and a control system is disclosed. The cartridge jaw comprises a distal end. The firing member comprises a knife edge configured to incise tissue. The drive screw is rotatable to drive the firing member toward the distal end during a staple firing stroke. The staples are deformed against the anvil iaw during the staple firing stroke. The control system is configured to limit the torque supplied by the electric motor to limit the force of the firing member and configured to control the speed of the electric motor.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application claiming priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 14/862,482, entitled SURGICAL CUTTING AND FASTENING INSTRUMENT HAVING RF ELECTRODES, filed Sep. 23, 2015, now U.S. Patent Application Pulication No. 10,265,067, which is a continuation application claiming priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 14/668,406, entitled SURGICAL CUTTING AND FASTENING INSTRUMENT HAVING RF ELECTRODES, filed Mar. 25, 2015, now U.S. Patent Application Publication No. 10,238,385, which is a continuation application claiming priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 12/031,573, entitled SURGICAL CUTTING AND FASTENING INSTRUMENT HAVING RF ELECTRODES, filed Feb. 14, 2008, the entire disclosures of which are hereby incorporated by reference herein.

The present application is related to and incorporates by reference the following applications which were filed on Feb. 14, 2008:

-   -   U.S. patent application Ser. No. 12/031,542, entitled MOTORIZED         SURGICAL CUTTING AND FASTENING INSTRUMENT HAVING A MAGNETIC         DRIVE TRAIN TORQUE LIMITING DEVICE, now U.S. Pat. No. 8,459,525;     -   U.S. patent application Ser. No. 12/031,556, entitled MOTORIZED         SURGICAL CUTTING AND FASTENING INSTRUMENT, now U.S. Pat. No.         8,636,736;     -   U.S. patent application Ser. No. 12/031,567, entitled MOTORIZED         SURGICAL CUTTING AND FASTENING INSTRUMENT HAVING HANDLE BASED         POWER SOURCE, now U.S. Pat. No. 8,657,174; and     -   U.S. patent application Ser. No. 12/031,580, entitled MOTORIZED         CUTTING AND FASTENING INSTRUMENT HAVING CONTROL CIRCUIT FOR         OPTIMIZING BATTERY USAGE, now U.S. Pat. No. 8,622,274.

BACKGROUND

Surgical staplers have been used in the prior art to simultaneously make a longitudinal incision in tissue and apply lines of staples on opposing sides of the incision. Such instruments commonly include a pair of cooperating jaw members that, if the instrument is intended for endoscopic or laparoscopic applications, are capable of passing through a cannula passageway. One of the jaw members receives a staple cartridge having at least two laterally spaced rows of staples. The other jaw member defines an anvil having staple-forming pockets aligned with the rows of staples in the cartridge. Such instruments typically include a plurality of reciprocating wedges that, when driven distally, pass through openings in the staple cartridge and engage drivers supporting the staples to effect the firing of the staples toward the anvil.

An example of a surgical stapler suitable for endoscopic applications is described in published U.S. Patent Application Publication No. 2004/0232196, entitled SURGICAL STAPLING INSTRUMENT HAVING SEPARATE DISTINCT CLOSING AND FIRING SYSTEMS, now U.S. Pat. No. 7,000,818, the disclosure of which is herein incorporated by reference. In use, a clinician is able to close the jaw members of the stapler upon tissue to position the tissue prior to firing. Once the clinician has determined that the jaw members are properly gripping tissue, the clinician can fire the surgical stapler, thereby severing and stapling the tissue. The simultaneous severing and stapling steps avoid complications that may arise when performing such actions sequentially with different surgical tools that respectively only sever or staple.

In addition, it is also known in the prior art to include electrodes in the end effector that can be used to emit/receive RF energy to form a hemostatic line along the cut line. U.S. Pat. No. 5,403,312, entitled ELECTROSURGICAL HEMOSTATIC DEVICE (hereinafter the “'312 Patent”), which is incorporated herein by reference, discloses an electrosurgical instrument with an end effector that compresses tissue between one pole (or electrode) of a bipolar energy source on one interfacing surface, and a second pole (or electrode) on a second interfacing surface. The RF energy is applied through the compressed tissue in the end effector, which cauterizes the tissue. The end effector described in the '312 Patent also includes staples for stapling the tissue compressed in the end effector.

Motor-powered surgical cutting and fastening instruments, where the motor powers the cutting instrument, are also known in the prior art, such as described in published U.S. Patent Application Publication No. 2007/0175962, entitled MOTOR-DRIVEN SURGICAL CUTTING AND FASTENING INSTRUMENT WITH TACTILE POSITION FEEDBACK, now U.S. Pat. No. 7,422,139, which is incorporated herein by reference.

SUMMARY

In one general aspect, embodiments of the present invention are directed to surgical cutting and fastening instruments. The instruments may be endoscopic instruments, such as linear endocutters or circular cutters, or laparoscopic instruments. The instruments may be comprised of staples and/or RF electrodes for fastening tissue clamped in the end effector.

Several embodiments disclosed herein are pertinent to cordless motor-powered instruments. The instruments may be powered by a power pack comprising a DC power source, such as one or more series-connected battery cells. A cell selection switch may control how many of the battery cells are being used to power the motor at a given time to control the power available to the motor. This allows the operator of the instrument to have greater control over both the speed and the power of the motor. In another embodiment, the instrument may comprise a power regulator, including, for example, a DC-to-DC converter, that regulates the voltage supplied to the motor. Further, the voltage set point for the power regulator could be set so that the voltage delivered from the power source is less than the voltage at which the power source delivers maximum power. That way, the power source (e.g., a number of series-connected battery cells) could operate on the “left” or increasing side of the power curve, so that increases in power would be available.

In addition, according to various embodiments, the power source may comprise secondary accumulator devices, such as rechargeable batteries or supercapacitors. Such secondary accumulator devices may be charged repeatably by replaceable batteries. A charge management circuit may control the charging of the secondary accumulator devices and provide various status signals, such as an alert, when the charging of the secondary accumulator devices is complete.

In other embodiment, a power pack comprising the secondary accumulator devices may be removable from the instrument and connectable to a remote charger base. The charger base may charge the secondary accumulator devices, such as from the AC electrical mains or a battery. The charger base may also comprise a processor and memory unit. Data stored in a memory of the removable power pack may be downloaded to the charger base, from which it may be uploaded for later use and analysis, such as by the user (e.g., physician), the manufacturer or distributor of the instrument, etc. The data may comprise operating parameters, such as charge cycle information, as well as ID values for various replaceable components of the instrument, such as the staple cartridge.

In addition, the instrument may comprise a torque-limiting device to limit the torque supplied by the motor, to limit thereby actuation forces that may damage components of the instrument. According to various embodiments, the torque-limiting devices may be an electromagnetic or permanent magnet, or mechanical clutch devices connected (either directly or indirectly) to the output pole of the motor.

In another general aspect, the present invention is directed to RF instruments (i.e., surgical cutting and fastening instruments with electrodes at the end effector for applying RF energy to the tissue held by the end effector) with new types of electrode configurations. In general, the new electrode configurations include combinations of smaller active electrodes and larger return electrodes. The smaller active electrodes are used to concentrate the therapeutic energy at the tissue, while the larger return electrodes preferentially are used to complete the circuit with minimal impact on that tissue interface. The return electrodes typically have greater mass and thereby are able to stay cooler during electrosurgical application.

In addition, the end effector, according to various embodiments, may comprise a number of co-linear, segmented active electrodes. The segmented electrodes could be energized synchronously or, more preferably, in sequence. Activating the segmented electrodes in sequence provides the advantages of (1) decreased instantaneous power requirements due to a smaller targeted area of tissue coagulation and (2) allowing other segments to fire if one is shorted out.

In addition, a number of mechanisms for activating the RF electrodes and for articulating the end effector are disclosed herein.

In various embodiments, a surgical instrument comprising a channel jaw, a replaceable cartridge body positioned in the channel jaw, staples removably stored in the replaceable cartridge body, a drive screw extending within the channel jaw, and a cutting member operably coupled to the drive screw is disclosed. The channel jaw comprises a distal end. The cutting member comprises a knife edge configured to incise tissue. The drive screw is rotatable to drive the cutting member toward the distal end during a staple firing stroke. The surgical instrument further comprises an anvil, an elongate shaft, and a rotatable shaft extending at least partially through the elongate shaft. The anvil comprises forming pockets configured to deform the staples during the staple firing stroke. The rotatable shaft is configured to rotate the drive screw to perform the staple firing stroke. The surgical instrument further comprises an electric motor configured to rotate the rotatable shaft and a control system configured to limit the torque supplied by the electric motor to limit the actuation force of the cutting member. The control system is further configured to control the speed of the electric motor.

In various embodiments, a surgical instrument assembly comprising a channel jaw, a cartridge positioned in the channel jaw, staples removably stored in the cartridge, a drive screw extending within the channel jaw, and a firing member drivable by the drive screw is disclosed. The channel jaw comprises a distal end. The firing member comprises a knife edge configured to incise tissue. The drive screw is rotatable to drive the firing member toward the distal end during a staple firing stroke. The surgical instrument assembly further comprises an anvil configured to deform the staples during the staple firing stroke, an elongate shaft, and a rotatable shaft extending at least partially through the elongate shaft. The rotatable shaft is operably coupled to the drive screw. The surgical instrument further comprises an electric motor configured to rotate the rotatable shaft and a control system configured to control the torque supplied by the electric motor to control the actuation force of the firing member. The control system is further configured to control the speed of the electric motor.

In various embodiments, a surgical instrument assembly comprising a cartridge jaw, a cartridge positioned in the cartridge jaw, staples removably stored in the cartridge, a drive screw extending within the cartridge jaw, a firing member operably engaged with the drive screw, an anvil jaw, an electric motor configured to rotate the drive screw, and a control system is disclosed. The cartridge jaw comprises a distal end. The firing member comprises a knife edge configured to incise tissue. The drive screw is rotatable to drive the firing member toward the distal end during a staple firing stroke. The staples are deformed against the anvil jaw during the staple firing stroke. The control system is configured to limit the torque supplied by the electric motor to limit the force of the firing member and configured to control the speed of the electric motor.

FIGURES

Various embodiments of the present invention are described herein by way of example in conjunction with the following figures, wherein:

FIGS. 1 and 2 are perspective views of a surgical cutting and fastening instrument according to various embodiments of the present invention;

FIGS. 3-5 are exploded views of an end effector and shaft of the instrument according to various embodiments of the present invention;

FIG. 6 is a side view of the end effector according to various embodiments of the present invention;

FIG. 7 is an exploded view of the handle of the instrument according to various embodiments of the present invention;

FIGS. 8 and 9 are partial perspective views of the handle according to various embodiments of the present invention;

FIG. 10 is a side view of the handle according to various embodiments of the present invention;

FIG. 11 is a schematic diagram of a circuit used in the instrument according to various embodiments of the present invention;

FIGS. 12-14 and 17 are schematic diagrams of circuits used to power the motor of the instrument according to various embodiments of the present invention;

FIG. 15 is a block diagram illustrating a charge management circuit according to various embodiments of the present invention;

FIG. 16 is a block diagram illustrating a charger base according to various embodiments of the present invention;

FIG. 18 illustrates a typical power curve of a battery;

FIGS. 19-22 illustrate embodiments of an electromagnetic, clutch-type torque-limiting device according to various embodiments of the present invention;

FIGS. 23-25, 27-28, and 59 are views of the lower surface of the anvil of the instrument according to various embodiments of the present invention;

FIGS. 26, 53, 54, and 68 are cross-sectional front views of the end effector according to various embodiments of the present invention;

FIGS. 29-32 show an embodiment of the end effector having RF electrodes according to various embodiments of the present invention;

FIGS. 33-36 show another embodiment of the end effector having RF electrodes according to various embodiments of the present invention;

FIGS. 37-40 show another embodiment of the end effector having RF electrodes according to various embodiments of the present invention;

FIGS. 41-44 show another embodiment of the end effector having RF electrodes according to various embodiments of the present invention;

FIGS. 45-48 show another embodiment of the end effector having RF electrodes according to various embodiments of the present invention;

FIGS. 49-52 show another embodiment of the end effector having RF electrodes according to various embodiments of the present invention;

FIGS. 55 and 56 show side views of the end effector according to various embodiments of the present invention;

FIG. 57 is a diagram of the handle of the instrument according to another embodiment of the present invention;

FIG. 58 is a cut-away view of the handle of the embodiment of FIG. 57 according to various embodiments of the present invention;

FIGS. 60-66 illustrate a multi-layer circuit board according to various embodiments of the present invention;

FIG. 67 is a diagram illustrating an end effector according to various embodiments of the present invention; and

FIGS. 69 and 70 are diagram of an instrument comprising a flexible neck assembly according to various embodiments of the present invention.

DESCRIPTION

FIGS. 1 and 2 depict a surgical cutting and fastening instrument 10 according to various embodiments of the present invention. The illustrated embodiment is an endoscopic instrument and, in general, the embodiments of the instrument 10 described herein are endoscopic surgical cutting and fastening instruments. It should be noted, however, that according to other embodiments of the present invention, the instrument may be a non-endoscopic surgical cutting and fastening instrument, such as a laparoscopic instrument.

The surgical instrument 10 depicted in FIGS. 1 and 2 comprises a handle 6, a shaft 8, and an articulating end effector 12 pivotally connected to the shaft 8 at an articulation pivot 14. An articulation control 16 may be provided adjacent to the handle 6 to effect rotation of the end effector 12 about the articulation pivot 14. In the illustrated embodiment, the end effector 12 is configured to act as an endocutter for clamping, severing and stapling tissue, although, in other embodiments, different types of end effectors may be used, such as end effectors for other types of surgical devices, such as graspers, cutters, staplers, clip appliers, access devices, drug/gene therapy devices, ultrasound, RF or laser devices, etc. More details regarding RF devices may be found in the '312 Patent.

The handle 6 of the instrument 10 may include a closure trigger 18 and a firing trigger 20 for actuating the end effector 12. It will be appreciated that instruments having end effectors directed to different surgical tasks may have different numbers or types of triggers or other suitable controls for operating the end effector 12. The end effector 12 is shown separated from the handle 6 by a preferably elongate shaft 8. In one embodiment, a clinician or operator of the instrument 10 may articulate the end effector 12 relative to the shaft 8 by utilizing the articulation control 16, as described in more detail in published U.S. Patent Application Publication No. 2007/0158385, entitled SURGICAL INSTRUMENT HAVING AN ARTICULATING END EFFECTOR, now U.S. Pat. No. 7,670,334, which is incorporated herein by reference.

The end effector 12 includes in this example, among other things, a staple channel 22 and a pivotally translatable clamping member, such as an anvil 24, which are maintained at a spacing that assures effective stapling and severing of tissue clamped in the end effector 12. The handle 6 includes a pistol grip 26 towards which a closure trigger 18 is pivotally drawn by the clinician to cause clamping or closing of the anvil 24 toward the staple channel 22 of the end effector 12 to thereby clamp tissue positioned between the anvil 24 and channel 22. The firing trigger 20 is farther outboard of the closure trigger 18. Once the closure trigger 18 is locked in the closure position as further described below, the firing trigger 20 may rotate slightly toward the pistol grip 26 so that it can be reached by the operator using one hand. Then the operator may pivotally draw the firing trigger 20 toward the pistol grip 12 to cause the stapling and severing of clamped tissue in the end effector 12. In other embodiments, different types of clamping members besides the anvil 24 could be used, such as, for example, an opposing jaw, etc.

It will be appreciated that the terms “proximal” and “distal” are used herein with reference to a clinician gripping the handle 6 of an instrument 10. Thus, the end effector 12 is distal with respect to the more proximal handle 6. It will be further appreciated that, for convenience and clarity, spatial terms such as “vertical” and “horizontal” are used herein with respect to the drawings. However, surgical instruments are used in many orientations and positions, and these terms are not intended to be limiting and absolute.

The closure trigger 18 may be actuated first. Once the clinician is satisfied with the positioning of the end effector 12, the clinician may draw back the closure trigger 18 to its fully closed, locked position proximate to the pistol grip 26. The firing trigger 20 may then be actuated. The firing trigger 20 returns to the open position (shown in FIGS. 1 and 2) when the clinician removes pressure, as described more fully below. A release button on the handle 6, when depressed may release the locked closure trigger 18. The release button may be implemented in various forms such as, for example, as a slide release button 160 shown in FIG. 7 or any of the mechanisms described in published U.S. Patent Application Publication No. 2007/0175955, which is incorporated herein by reference.

FIG. 3 is an exploded view of the end effector 12 according to various embodiments. As shown in the illustrated embodiment, the end effector 12 may include, in addition to the previously mentioned channel 22 and anvil 24, a cutting instrument 32, a sled 33, a staple cartridge 34 that is removably seated in the channel 22, and a helical screw shaft 36. The cutting instrument 32 may be, for example, a knife. The anvil 24 may be pivotably opened and closed at a pivot point 25 connected to the proximate end of the channel 22. The anvil 24 may also include a tab 27 at its proximate end that is inserted into a component of the mechanical closure system (described further below) to open and close the anvil 24. When the closure trigger 18 is actuated, that is, drawn in by a user of the instrument 10, the anvil 24 may pivot about the pivot point 25 into the clamped or closed position. If clamping of the end effector 12 is satisfactory, the operator may actuate the firing trigger 20, which, as explained in more detail below, causes the knife 32 and sled 33 to travel longitudinally along the channel 22, thereby cutting tissue clamped within the end effector 12. The movement of the sled 33 along the channel 22 causes the staples of the staple cartridge 34 to be driven through the severed tissue and against the closed anvil 24, which turns the staples to fasten the severed tissue. In various embodiments, the sled 33 may be an integral component of the cartridge 34. U.S. Pat. No. 6,978,921, entitled SURGICAL STAPLING INSTRUMENT INCORPORATING AN E-BEAM FIRING MECHANISM, which is incorporated herein by reference, provides more details about such two-stroke cutting and fastening instruments. The sled 33 may be part of the cartridge 34, such that when the knife 32 retracts following the cutting operation, the sled 33 does not retract.

It should be noted that although the embodiments of the instrument 10 described herein employ an end effector 12 that staples the severed tissue, in other embodiments different techniques for fastening or sealing the severed tissue may be used. For example, end effectors that use RF energy or adhesives to fasten the severed tissue may also be used. U.S. Pat. No. 5,709,680 entitled ELECTROSURGICAL HEMOSTATIC DEVICE, and U.S. Pat. No. 5,688,270 entitled ELECTROSURGICAL HEMOSTATIC DEVICE WITH RECESSED AND/OR OFFSET ELECTRODES, which are incorporated herein by reference, disclose an endoscopic cutting instrument that uses RF energy to seal the severed tissue. Published U.S. Patent Application Publication No. 2007/0102453, now U.S. Pat. No. 7,673,783 and published U.S. Patent Application Publication No. 2007/0102452, now U.S. Pat. No. 7,607,557, which are also incorporated herein by reference, disclose endoscopic cutting instruments that use adhesives to fasten the severed tissue. Accordingly, although the description herein refers to cutting/stapling operations and the like below, it should be recognized that this is an exemplary embodiment and is not meant to be limiting. Other tissue-fastening techniques may also be used.

FIGS. 4 and 5 are exploded views and FIG. 6 is a side view of the end effector 12 and shaft 8 according to various embodiments. As shown in the illustrated embodiment, the shaft 8 may include a proximate closure tube 40 and a distal closure tube 42 pivotably linked by a pivot links 44. The distal closure tube 42 includes an opening 45 into which the tab 27 on the anvil 24 is inserted in order to open and close the anvil 24, as further described below. Disposed inside the closure tubes 40, 42 may be a proximate spine tube 46. Disposed inside the proximate spine tube 46 may be a main rotational (or proximate) drive shaft 48 that communicates with a secondary (or distal) drive shaft 50 via a bevel gear assembly 52. The secondary drive shaft 50 is connected to a drive gear 54 that engages a proximate drive gear 56 of the helical screw shaft 36. The vertical bevel gear 52 b may sit and pivot in an opening 57 in the distal end of the proximate spine tube 46. A distal spine tube 58 may be used to enclose the secondary drive shaft 50 and the drive gears 54, 56. Collectively, the main drive shaft 48, the secondary drive shaft 50, and the articulation assembly (e.g., the bevel gear assembly 52 a-c) are sometimes referred to herein as the “main drive shaft assembly.”

A bearing 38, positioned at a distal end of the staple channel 22, receives the helical drive screw 36, allowing the helical drive screw 36 to freely rotate with respect to the channel 22. The helical screw shaft 36 may interface a threaded opening (not shown) of the knife 32 such that rotation of the shaft 36 causes the knife 32 to translate distally or proximately (depending on the direction of the rotation) through the staple channel 22. Accordingly, when the main drive shaft 48 is caused to rotate by actuation of the firing trigger 20 (as explained in more detail below), the bevel gear assembly 52 a-c causes the secondary drive shaft 50 to rotate, which in turn, because of the engagement of the drive gears 54, 56, causes the helical screw shaft 36 to rotate, which causes the knife driving member 32 to travel longitudinally along the channel 22 to cut any tissue clamped within the end effector. The sled 33 may be made of, for example, plastic, and may have a sloped distal surface. As the sled 33 traverses the channel 22, the sloped forward surface may push up or drive the staples in the staple cartridge through the clamped tissue and against the anvil 24. The anvil 24 turns the staples, thereby stapling the severed tissue. When the knife 32 is retracted, the knife 32 and sled 33 may become disengaged, thereby leaving the sled 33 at the distal end of the channel 22.

FIGS. 7-10 illustrate an exemplary embodiment of a motor-driven endocutter. The illustrated embodiment provides user-feedback regarding the deployment and loading force of the cutting instrument in the end effector. In addition, the embodiment may use power provided by the user in retracting the firing trigger 20 to power the device (a so-called “power assist” mode). As shown in the illustrated embodiment, the handle 6 includes exterior lower side pieces 59, 60 and exterior upper side pieces 61, 62 that fit together to form, in general, the exterior of the handle 6. A battery 64, such as a Li ion battery, may be provided in the pistol grip portion 26 of the handle 6. The battery 64 powers a motor 65 disposed in an upper portion of the pistol grip portion 26 of the handle 6. According to various embodiments, a number of battery cells connected in series may be used to power the motor 65.

The motor 65 may be a DC brushed driving motor having a maximum rotation of approximately 25,000 RPM with no load. The motor 64 may drive a 90° bevel gear assembly 66 comprising a first bevel gear 68 and a second bevel gear 70. The bevel gear assembly 66 may drive a planetary gear assembly 72. The planetary gear assembly 72 may include a pinion gear 74 connected to a drive shaft 76. The pinion gear 74 may drive a mating ring gear 78 that drives a helical gear drum 80 via a drive shaft 82. A ring 84 may be threaded on the helical gear drum 80. Thus, when the motor 65 rotates, the ring 84 is caused to travel along the helical gear drum 80 by means of the interposed bevel gear assembly 66, planetary gear assembly 72, and ring gear 78.

The handle 6 may also include a run motor sensor 110 in communication with the firing trigger 20 to detect when the firing trigger 20 has been drawn in (or “closed”) toward the pistol grip portion 26 of the handle 6 by the operator to thereby actuate the cutting/stapling operation by the end effector 12. The sensor 110 may be a proportional sensor such as, for example, a rheostat, or variable resistor. When the firing trigger 20 is drawn in, the sensor 110 detects the movement, and sends an electrical signal indicative of the voltage (or power) to be supplied to the motor 65. When the sensor 110 is a variable resistor or the like, the rotation of the motor 65 may be generally proportional to the amount of movement of the firing trigger 20. That is, if the operator only draws or closes the firing trigger 20 in a little bit, the rotation of the motor 65 is relatively low. When the firing trigger 20 is fully drawn in (or in the fully closed position), the rotation of the motor 65 is at its maximum. In other words, the harder the user pulls on the firing trigger 20, the more voltage is applied to the motor 65, causing greater rates of rotation.

The handle 6 may include a middle handle piece 104 adjacent to the upper portion of the firing trigger 20. The handle 6 also may comprise a bias spring 112 connected between posts on the middle handle piece 104 and the firing trigger 20. The bias spring 112 may bias the firing trigger 20 to its fully open position. In that way, when the operator releases the firing trigger 20, the bias spring 112 will pull the firing trigger 20 to its open position, thereby removing actuation of the sensor 110, thereby stopping rotation of the motor 65. Moreover, by virtue of the bias spring 112, any time a user closes the firing trigger 20, the user will experience resistance to the closing operation, thereby providing the user with feedback as to the amount of rotation exerted by the motor 65. Further, the operator could stop retracting the firing trigger 20 to thereby remove force from the sensor 100, to thereby stop the motor 65. As such, the user may stop the deployment of the end effector 12, thereby providing a measure of control of the cutting/fastening operation to the operator.

The distal end of the helical gear drum 80 includes a distal drive shaft 120 that drives a ring gear 122, which mates with a pinion gear 124. The pinion gear 124 is connected to the main drive shaft 48 of the main drive shaft assembly. In that way, rotation of the motor 65 causes the main drive shaft assembly to rotate, which causes actuation of the end effector 12, as described above.

The ring 84 threaded on the helical gear drum 80 may include a post 86 that is disposed within a slot 88 of a slotted arm 90. The slotted arm 90 has an opening 92 at its opposite end 94 that receives a pivot pin 96 that is connected between the handle exterior side pieces 59, 60. The pivot pin 96 is also disposed through an opening 100 in the firing trigger 20 and an opening 102 in the middle handle piece 104.

In addition, the handle 6 may include a reverse motor (or end-of-stroke sensor) 130 and a stop motor (or beginning-of-stroke) sensor 142. In various embodiments, the reverse motor sensor 130 may be a limit switch located at the distal end of the helical gear drum 80 such that the ring 84 threaded on the helical gear drum 80 contacts and trips the reverse motor sensor 130 when the ring 84 reaches the distal end of the helical gear drum 80. The reverse motor sensor 130, when activated, sends a signal to the motor 65 to reverse its rotation direction, thereby withdrawing the knife 32 of the end effector 12 following the cutting operation. The stop motor sensor 142 may be, for example, a normally-closed limit switch. In various embodiments, it may be located at the proximate end of the helical gear drum 80 so that the ring 84 trips the switch 142 when the ring 84 reaches the proximate end of the helical gear drum 80.

In operation, when an operator of the instrument 10 pulls back the firing trigger 20, the sensor 110 detects the deployment of the firing trigger 20 and sends a signal to the motor 65 to cause forward rotation of the motor 65 at, for example, a rate proportional to how hard the operator pulls back the firing trigger 20. The forward rotation of the motor 65 in turn causes the ring gear 78 at the distal end of the planetary gear assembly 72 to rotate, thereby causing the helical gear drum 80 to rotate, causing the ring 84 threaded on the helical gear drum 80 to travel distally along the helical gear drum 80. The rotation of the helical gear drum 80 also drives the main drive shaft assembly as described above, which in turn causes deployment of the knife 32 in the end effector 12. That is, the knife 32 and sled 33 are caused to traverse the channel 22 longitudinally, thereby cutting tissue clamped in the end effector 12. Also, the stapling operation of the end effector 12 is caused to happen in embodiments where a stapling-type end effector is used.

By the time the cutting/stapling operation of the end effector 12 is complete, the ring 84 on the helical gear drum 80 will have reached the distal end of the helical gear drum 80, thereby causing the reverse motor sensor 130 to be tripped, which sends a signal to the motor 65 to cause the motor 65 to reverse its rotation. This in turn causes the knife 32 to retract, and also causes the ring 84 on the helical gear drum 80 to move back to the proximate end of the helical gear drum 80.

The middle handle piece 104 includes a backside shoulder 106 that engages the slotted arm 90 as best shown in FIGS. 8 and 9. The middle handle piece 104 also has a forward motion stop 107 that engages the firing trigger 20. The movement of the slotted arm 90 is controlled, as explained above, by rotation of the motor 65. When the slotted arm 90 rotates CCW as the ring 84 travels from the proximate end of the helical gear drum 80 to the distal end, the middle handle piece 104 will be free to rotate CCW. Thus, as the user draws in the firing trigger 20, the firing trigger 20 will engage the forward motion stop 107 of the middle handle piece 104, causing the middle handle piece 104 to rotate CCW. Due to the backside shoulder 106 engaging the slotted arm 90, however, the middle handle piece 104 will only be able to rotate CCW as far as the slotted arm 90 permits. In that way, if the motor 65 should stop rotating for some reason, the slotted arm 90 will stop rotating, and the user will not be able to further draw in the firing trigger 20 because the middle handle piece 104 will not be free to rotate CCW due to the slotted arm 90.

Components of an exemplary closure system for closing (or clamping) the anvil 24 of the end effector 12 by retracting the closure trigger 18 are also shown in FIGS. 7-10. In the illustrated embodiment, the closure system includes a yoke 250 connected to the closure trigger 18 by a pin 251 that is inserted through aligned openings in both the closure trigger 18 and the yoke 250. A pivot pin 252, about which the closure trigger 18 pivots, is inserted through another opening in the closure trigger 18 which is offset from where the pin 251 is inserted through the closure trigger 18. Thus, retraction of the closure trigger 18 causes the upper part of the closure trigger 18, to which the yoke 250 is attached via the pin 251, to rotate CCW. The distal end of the yoke 250 is connected, via a pin 254, to a first closure bracket 256. The first closure bracket 256 connects to a second closure bracket 258. Collectively, the closure brackets 256, 258 define an opening in which the proximate end of the proximate closure tube 40 (see FIG. 4) is seated and held such that longitudinal movement of the closure brackets 256, 258 causes longitudinal motion by the proximate closure tube 40. The instrument 10 also includes a closure rod 260 disposed inside the proximate closure tube 40. The closure rod 260 may include a window 261 into which a post 263 on one of the handle exterior pieces, such as exterior lower side piece 59 in the illustrated embodiment, is disposed to fixedly connect the closure rod 260 to the handle 6. In that way, the proximate closure tube 40 is capable of moving longitudinally relative to the closure rod 260. The closure rod 260 may also include a distal collar 267 that fits into a cavity 269 in proximate spine tube 46 and is retained therein by a cap 271 (see FIG. 4).

In operation, when the yoke 250 rotates due to retraction of the closure trigger 18, the closure brackets 256, 258 cause the proximate closure tube 40 to move distally (i.e., away from the handle end of the instrument 10), which causes the distal closure tube 42 to move distally, which causes the anvil 24 to rotate about the pivot point 25 into the clamped or closed position. When the closure trigger 18 is unlocked from the locked position, the proximate closure tube 40 is caused to slide proximately, which causes the distal closure tube 42 to slide proximately, which, by virtue of the tab 27 being inserted in the window 45 of the distal closure tube 42, causes the anvil 24 to pivot about the pivot point 25 into the open or unclamped position. In that way, by retracting and locking the closure trigger 18, an operator may clamp tissue between the anvil 24 and channel 22, and may unclamp the tissue following the cutting/stapling operation by unlocking the closure trigger 20 from the locked position.

FIG. 11 is a schematic diagram of an electrical circuit of the instrument 10 according to various embodiments of the present invention. When an operator initially pulls in the firing trigger 20 after locking the closure trigger 18, the sensor 110 is activated, allowing current to flow there through. If the normally-open reverse motor sensor switch 130 is open (meaning the end of the end effector stroke has not been reached), current will flow to a single pole, double throw relay 132. Since the reverse motor sensor switch 130 is not closed, the inductor 134 of the relay 132 will not be energized, so the relay 132 will be in its non-energized state. The circuit also includes a cartridge lockout sensor 136. If the end effector 12 includes a staple cartridge 34, the sensor 136 will be in the closed state, allowing current to flow. Otherwise, if the end effector 12 does not include a staple cartridge 34, the sensor 136 will be open, thereby preventing the battery 64 from powering the motor 65.

When the staple cartridge 34 is present, the sensor 136 is closed, which energizes a single pole, single throw relay 138. When the relay 138 is energized, current flows through the relay 136, through the variable resistor sensor 110, and to the motor 65 via a double pole, double throw relay 140, thereby powering the motor 65, and allowing it to rotate in the forward direction. When the end effector 12 reaches the end of its stroke, the reverse motor sensor 130 will be activated, thereby closing the switch 130 and energizing the relay 134. This causes the relay 134 to assume its energized state (not shown in FIG. 13), which causes current to bypass the cartridge lockout sensor 136 and variable resistor 110, and instead causes current to flow to both the normally-closed double pole, double throw relay 142 and back to the motor 65, but in a manner, via the relay 140, that causes the motor 65 to reverse its rotational direction. Because the stop motor sensor switch 142 is normally closed, current will flow back to the relay 134 to keep it closed until the switch 142 opens. When the knife 32 is fully retracted, the stop motor sensor switch 142 is activated, causing the switch 142 to open, thereby removing power from the motor 65.

In other embodiments, rather than a proportional-type sensor 110, an on-off type sensor could be used. In such embodiments, the rate of rotation of the motor 65 would not be proportional to the force applied by the operator. Rather, the motor 65 would generally rotate at a constant rate. But the operator would still experience force feedback because the firing trigger 20 is geared into the gear drive train.

Additional configurations for motorized surgical instruments are disclosed in published U.S. Patent Application Publication No. 2007/0175962, entitled MOTOR-DRIVEN SURGICAL CUTTING AND FASTENING INSTRUMENT WITH TACTILE POSITION FEEDBACK, now U.S. Pat. No. 7,422,139, which is incorporated herein by reference.

In a motorized surgical instrument, such as one of the motorized endoscopic instruments described above or in a motorized circular cutter instrument, the motor may be powered by a number of battery cells connected in series. Further, it may be desirable in certain circumstances to power the motor with some fraction of the total number of battery cells. For example, as shown in FIG. 12, the motor 65 may be powered by a power pack 299 comprising six (6) battery cells 310 connected in series. The battery cells 310 may be, for example, 3-volt lithium battery cells, such as CR 123A battery cells, although in other embodiments, different types of battery cells could be used (including battery cells with different voltage levels and/or different chemistries). If six 3-volt battery cells 310 were connected in series to power the motor 65, the total voltage available to power the motor 65 would be 18 volts. The battery cells 310 may comprise rechargeable or non-rechargeable battery cells.

In such an embodiment, under the heaviest loads, the input voltage to the motor 65 may sag to about nine to ten volts. At this operating condition, the power pack 299 is delivering maximum power to the motor 65. Accordingly, as shown in FIG. 12, the circuit may include a switch 312 that selectively allows the motor 65 to be powered by either (1) all of the battery cells 310 or (2) a fraction of the battery cells 310. As shown in FIG. 12, by proper selection, the switch 312 may allow the motor 65 to be powered by all six battery cells or four of the battery cells. That way, the switch 312 could be used to power the motor 65 with either 18 volts (when using all six battery cells 310) or 12 volts (such using four of the second battery cells). In various embodiments, the design choice for the number of battery cells in the fraction that is used to power the motor 65 may be based on the voltage required by the motor 65 when operating at maximum output for the heaviest loads.

The switch 312 may be, for example, an electromechanical switch, such as a micro switch. In other embodiments, the switch 312 may be implemented with a solid-state switch, such as transistor. A second switch 314, such as a push button switch, may be used to control whether power is applied to the motor 65 at all. Also, a forward/reverse switch 316 may be used to control whether the motor 65 rotates in the forward direction or the reverse direction. The forward/reverse switch 316 may be implemented with a double pole-double throw switch, such as the relay 140 shown in FIG. 11.

In operation, the user of the instrument 10 could select the desired power level by using some sort of switch control, such as a position-dependent switch (not shown), such as a toggle switch, a mechanical lever switch, or a cam, which controls the position of the switch 312. Then the user may activate the second switch 314 to connect the selected battery cells 310 to the motor 65. In addition, the circuit shown in FIG. 12 could be used to power the motor of other types of motorized surgical instruments, such as circular cutters and/or laparoscopic instruments. More details regarding circular cutters may be found in published U.S. Patent Application Publication Nos. 2006/0047307, now U.S. Pat. No. 8,317,074 and 2007/0262116, now U.S. Pat. No. 7,500,979, which are incorporated herein by reference.

In other embodiments, as shown in FIG. 13, a primary power source 340, such as a battery cell, such as a CR2 or CR123A battery cell, may be used to charge a number of secondary accumulator devices 342. The primary power source 340 may comprise one or a number of series-connected battery cells, which are preferably replaceable in the illustrated embodiment. The secondary accumulator devices 342 may comprise, for example, rechargeable battery cells and/or supercapacitors (also known as “ultracapacitors” or “electrochemical double layer capacitors” (EDLC)). Supercapacitors are electrochemical capacitors that have an unusually high energy density when compared to common electrolytic capacitors, typically on the order of thousands of times greater than a high-capacity electrolytic capacitor.

The primary power source 340 may charge the secondary accumulator devices 342. Once sufficiently charged, the primary power source 340 may be removed and the secondary accumulator devices 342 may be used to power the motor 65 during a procedure or operation. The accumulating devices 342 may take about fifteen to thirty minutes to charge in various circumstances. Supercapacitors have the characteristic they can charge and discharge extremely rapidly in comparison to conventional batteries. In addition, whereas batteries are good for only a limited number of charge/discharge cycles, supercapacitors can often be charged/discharged repeatedly, sometimes for tens of millions of cycles. For embodiments using supercapacitors as the secondary accumulator devices 342, the supercapacitors may comprise carbon nanotubes, conductive polymers (e.g., polyacenes), or carbon aerogels.

As shown in FIG. 14, a charge management circuit 344 could be employed to determine when the secondary accumulator devices 342 are sufficiently charged. The charge management circuit 344 may include an indicator, such as one or more LEDs, an LCD display, etc., that is activated to alert a user of the instrument 10 when the secondary accumulator devices 342 are sufficiently charged.

The primary power source 340, the secondary accumulator devices 342, and the charge management circuit 344 may be part of a power pack in the pistol grip portion 26 of the handle 6 of the instrument 10, or in another part of the instrument 10. The power pack may be removable from the pistol grip portion 26, in which case, when the instrument 10 is to be used for surgery, the power pack may be inserted aseptically into the pistol grip portion 26 (or other position in the instrument according to other embodiments) by, for example, a circulating nurse assisting in the surgery. After insertion of the power pack, the nurse could put the replaceable primary power source 340 in the power pack to charge up the secondary accumulator devices 342 a certain time period prior to use of the instrument 10, such as thirty minutes. When the secondary accumulator devices 342 are charged, the charge management circuit 344 may indicate that the power pack is ready for use. At this point, the replaceable primary power source 340 may be removed. During the operation, the user of the instrument 10 may then activate the motor 65, such as by activating the switch 314, whereby the secondary accumulator devices 342 power the motor 65. Thus, instead of having a number of disposable batteries to power the motor 65, one disposable battery (as the primary power source 340) could be used in such an embodiment, and the secondary accumulator devices 342 could be reusable. In alternative embodiments, however, it should be noted that the secondary accumulator devices 342 could be non-rechargeable and/or non-reusable. The secondary accumulators 342 may be used with the cell selection switch 312 described above in connection with FIG. 12.

The charge management circuit 344 may also include indicators (e.g., LEDs or LCD display) that indicate how much charge remains in the secondary accumulator devices 342. That way, the surgeon (or other user of the instrument 10) can see how much charge remains through the course of the procedure involving the instrument 10.

The charge management circuit 344, as shown in FIG. 15, may comprise a charge meter 345 for measuring the charge across the secondary accumulators 342. The charge management circuit 344 also may comprise a non-volatile memory 346, such as flash or ROM memory, and one or more processors 348. The processor(s) 348 may be connected to the memory 346 to control the memory. In addition, the processor(s) 348 may be connected to the charge meter 345 to read the readings of and otherwise control the charge meter 345. Additionally, the processor(s) 348 may control the LEDs or other output devices of the charge management circuit 344. The processor(s) 348 can store parameters of the instrument 10 in the memory 346. The parameters may include operating parameters of the instrument that are sensed by various sensors that may be installed or employed in the instrument 10, such as, for example, the number of firings, the levels of forces involved, the distance of the compression gap between the opposing jaws of the end effector 12, the amount of articulation, etc. Additionally, the parameters stored in the memory 346 may comprise ID values for various components of the instrument 10 that the charge management circuit 344 may read and store. The components having such IDs may be replaceable components, such as the staple cartridge 34. The IDs may be for example, RFIDs that the charge management circuit 344 reads via a RFID transponder 350. The RFID transponder 350 may read RFIDs from components of the instrument, such as the staple cartridge 34, that include RFID tags. The ID values may be read, stored in the memory 346, and compared by the processor 348 to a list of acceptable ID values stored in the memory 346 or another store associated with the charge management circuit, to determine, for example, if the removable/replaceable component associated with the read ID value is authentic and/or proper. According to various embodiments, if the processor 348 determines that the removable/replaceable component associated with the read ID value is not authentic, the charge management circuit 344 may prevent use of the power pack by the instrument 10, such as by opening a switch (not shown) that would prevent power from the power pack being delivered to the motor 65. According to various embodiments, various parameters that the processor 348 may evaluate to determine whether the component is authentic and/or proper include: date code; component model/type; manufacturer; regional information; and previous error codes.

The charge management circuit 344 may also comprise an i/o interface 352 for communicating with another device, such as described below. That way, the parameters stored in the memory 346 may be downloaded to another device. The i/o interface 352 may be, for example, a wired or wireless interface.

As mentioned before, the power pack may comprise the secondary accumulators 342, the charge management circuit 344, and/or the f/r switch 316. According to various embodiments, as shown in FIG. 16, the power pack 299 could be connected to a charger base 362, which may, among other things, charge the secondary accumulators 342 in the power pack. The charger base 362 could be connected to the power pack 299 by connecting aseptically the charger base 362 to the power pack 299 while the power pack is installed in the instrument 10. In other embodiments where the power pack is removable, the charger base 362 could be connected to the power pack 299 by removing the power pack 299 from the instrument 10 and connecting it to the charger base 362. For such embodiments, after the charger base 362 sufficiently charges the secondary accumulators 342, the power pack 299 may be aseptically installed in the instrument 10.

As shown in FIG. 16, the charger base 362 may comprise a power source 364 for charging the secondary accumulators 342. The power source 364 of the charger base 362 may be, for example, a battery (or a number of series-connected batteries), or an AC/DC converter that converters AC power, such as from electrical power mains, to DC, or any other suitable power source for charging the secondary accumulators 342. The charger base 362 may also comprise indicator devices, such as LEDs, a LCD display, etc., to show the charge status of the secondary accumulators 342.

In addition, as shown in FIG. 16, the charger base 362 may comprise one or more processors 366, one or more memory units 368, and i/o interfaces 370, 372. Through the first i/o interface 370, the charger base 362 may communicate with the power pack 299 (via the power pack's i/o interface 352). That way, for example, data stored in the memory 346 of the power pack 299 may be downloaded to the memory 368 of the charger base 362. In that way, the processor 366 can evaluate the ID values for the removable/replaceable components, downloaded from the charge management circuit 344, to determine the authenticity and suitability of the components. The operating parameters downloaded from the charge management circuit 344 may also stored in the memory 368, and then may then be downloaded to another computer device via the second i/o interface 372 for evaluation and analysis, such as by the hospital system in which the operation involving the instrument 10 is performed, by the office of the surgeon, by the distributor of the instrument, by the manufacturer of the instrument, etc.

The charger base 362 may also comprise a charge meter 374 for measuring the charge across the secondary accumulators 342. The charge meter 374 may be in communication with the processor(s) 366, so that the processor(s) 366 can determine in real-time the suitability of the power pack 299 for use to ensure high performance.

In another embodiment, as shown in FIG. 17, the battery circuit may comprise a power regulator 320 to control the power supplied by the power savers 310 to the motor 65. The power regulator 320 may also be part of the power pack 299, or it may be a separate component. As mentioned above, the motor 65 may be a brushed DC motor. The speed of brushed DC motors generally is proportional to the applied input voltage. The power regulator 320 may provide a highly regulated output voltage to the motor 65 so that the motor 65 will operate at a constant (or substantially constant) speed. According to various embodiments, the power regulator 320 may comprise a switch-mode power converter, such as a buck-boost converter, as shown in the example of FIG. 17. Such a buck-boost converter 320 may comprise a power switch 322, such as a FET, a rectifier 324, an inductor 326, and a capacitor 328. When the power switch 322 is on, the input voltage source (e.g., the power sources 310) is directly connected to the inductor 326, which stores energy in this state. In this state, the capacitor 328 supplies energy to the output load (e.g., the motor 65). When the power switch 320 is in the off state, the inductor 326 is connected to the output load (e.g., the motor 65) and the capacitor 328, so energy is transferred from the inductor 326 to the capacitor 328 and the load 65. A control circuit 330 may control the power switch 322. The control circuit 330 may employ digital and/or analog control loops. In addition, in other embodiments, the control circuit 330 may receive control information from a master controller (not shown) via a communication link, such as a serial or parallel digital data bus. The voltage set point for the output of the power regulator 320 may be set, for example, to one-half of the open circuit voltage, at which point the maximum power available from the source is available.

In other embodiments, different power converter topologies may be employed, including linear or switch-mode power converters. Other switch-mode topologies that may be employed include a flyback, forward, buck, boost, and SEPIC. The set point voltage for the power regulator 320 could be changed depending on how many of the battery cells are being used to power the motor 65. Additionally, the power regulator 320 could be used with the secondary accumulator devices 342 shown in FIG. 13. Further, the forward-reverse switch 316 could be incorporated into the power regulator 320, although it is shown separately in FIG. 17.

Batteries can typically be modeled as an ideal voltage source and a source resistance. For an ideal model, when the source and load resistance are matched, maximum power is transferred to the load. FIG. 18 shows a typical power curve for a battery. When the battery circuit is open, the voltage across the battery is high (at its open circuit value) and the current drawn from the battery is zero. The power delivered from the battery is zero also. As more current is drawn from the battery, the voltage across the battery decreases. The power delivered by the battery is the product of the current and the voltage. The power reaches its peak around at a voltage level that is less than the open circuit voltage. As shown in FIG. 18, with most battery chemistries there is a sharp drop in the voltage/power at higher current because of the chemistry or positive temperature coefficient (PTC), or because of a battery protection device.

Particularly for embodiments using a battery (or batteries) to power the motor 65 during a procedure, the control circuit 330 can monitor the output voltage and control the set point of the regulator 320 so that the battery operates on the “left” or power-increasing side of the power curve. If the battery reaches the peak power level, the control circuit 330 can change (e.g., lower) the set point of the regulator so that less total power is being demanded from the battery. The motor 65 would then slow down. In this way, the demand from the power pack would rarely if ever exceed the peak available power so that a power-starving situation during a procedure could be avoided.

In addition, according to other embodiments, the power drawn from the battery may be optimized in such a way that the chemical reactions within the battery cells would have time to recover, to thereby optimize the current and power available from the battery. In pulsed loads, batteries typically provide more power at the beginning of the pulse that toward the end of the pulse. This is due to several factors, including: (1) the PTC may be changing its resistance during the pulse; (2) the temperature of the battery may be changing; and (3) the electrochemical reaction rate is changing due to electrolyte at the cathode being depleted and the rate of diffusion of the fresh electrolyte limits the reaction rate. According to various embodiments, the control circuit 330 may control the converter 320 so that it draws a lower current from the battery to allow the battery to recover before it is pulsed again.

According to other embodiments, the instrument 10 may comprise a clutch-type torque-limiting device. The clutch-type torque-limiting device may be located, for example, between the motor 65 and the bevel gear 68, between the bevel gear 70 and the planetary gear assembly 72, or on the output shaft of the planetary gear assembly 72. According to various embodiments, the torque-limiting device may use an electromagnetic or permanent magnetic clutch.

FIGS. 19 to 22 show a sample electromagnetic clutch 400 that could be used in the instrument 10 according to various embodiments. The clutch 400 may comprise a horseshoe-shaped stator 402 having magnetic disks 404, 406 at each end. The first disk 404 may be connected to an axially movable, rotatable pole piece 408, such as the output pole of the motor 65. The second magnetic disk 406 may be connected to an axially stationary, rotatable pole piece 410, such as an input pole to a gear box of the instrument 10. In the views of FIGS. 19 and 20, the first pole piece 408 is axially pulled away from the second pole piece 410 by a clearance 412 such that the magnetic disks 404, 406 are not engaged. A wire coil (not shown), which may be wrapped around the stator 402 may be used to create the electromagnetic flux needed to actuate the clutch 400. When the coil conducts an electrical current, the resulting magnetic flux may cause the two magnetic disks 404, 406 to attract, causing the first pole piece 408 to move axially toward the second pole piece 410, thereby causing the two magnetic disks 404, 406 to become engaged, as shown in FIGS. 21 and 22, such that the two pole pieces 408, 410 will rotate together until the torque exceeds the friction torque generated between the faces of magnetic disks 404 and 406.

The attractive force between the two disks 404, 406 and the corresponding torque capacity of the clutch 400 could be controlled by controlling the diameter of the disks 404, 406, the coefficient of friction between the contacting faces of magnetic disks 404 and 406, and by using magnetic materials for the disks 404, 406 that saturate at a known and controllable flux density. Therefore, even if there was an operating condition where more current was passed through the coil, the magnetic material of the disks 404, 406 would not generate a greater attractive force and subsequent limiting torque.

Utilization of such a clutch has many additional potential benefits. Being electrically controlled, the clutch 400 could be quickly deactivated by removing current from the wire to limit the amount of heat generated within the clutch 400 and within the motor 65. By disconnecting the motor from the rest of the drive train, via the clutch 400, most of the stored inertial energy in the drive train would be disconnected, limiting shock if the output were to be blocked suddenly. In addition, by being electrically controlled, some limited slipping could be designed-in to aid in reducing shocks when restarting the drive train under load. Further, because the magnetic saturation properties of one or more of the components (e.g., the magnetic disks 404, 406) within the clutch could be used to control the torque limit instead of coil current, the clutch 400 would be less sensitive to changes in system voltage. The torque limit in such embodiments would be primarily a function of the physical dimensions of the components of the clutch (e.g., the magnetic disks 404, 406) and would not require voltage regulators or other external components for proper operation.

In another embodiment, rather than using an electromagnetic clutch, the torque-limiting device may comprise a permanent magnet (not shown). The permanent magnet may be connected, for example, to the first, axially-movable, pole piece 408, and attract the axially-fixed second pole piece 410, or vice versa. In such embodiments, one of the disks 404, 406 could be made of a permanent magnet and the other one of a magnetic material like iron. In a slight variation, the stator 402 could be made in the form of a permanent magnet, causing the magnetic disks 404 and 406 to be attracted to each other. Because of the permanent magnet, the two disks 404, 406 would be engaged always. Using a permanent magnet would not provide as accurate as torque control as the electromagnetic clutch configuration described above, but it would have the advantages of: (1) not requiring controls or control logic to control the current through the coil; (2) being more compact that the electromagnetic clutch configuration; and (3) simplifying design of the instrument 10.

As mentioned previously, the end effector 12 may emit RF energy to coagulate tissue clamped in the end effector. The RF energy may be transmitted between electrodes in the end effector 12. A RF source (not shown), comprising, for example, an oscillator and an amplifier, among other components, which may supply the RF energy to the electrode, may be located in the instrument itself, such as in the handle 6 for a cordless instrument 10, or the RF source may be external to the instrument 10. The RF source may be activated as described further below.

According to various embodiments, the end effector 12 may comprise multiple sections (or segments) of electrodes. For example, as shown in the example of FIG. 23, the lower surface of the anvil 24 (i.e., the surface facing the staple cartridge 34) may comprise three co-linear RF segments. In this example, each segment has the same length (e.g., 20 mm), although in other embodiments there may be more or fewer segments, and the segments may have different lengths. In the example of FIG. 23, there are three pairs of active or “anode” terminals or electrodes 500 lined up longitudinally along each side of the channel length on the lower surface of the anvil 24. In particular, in the illustrated embodiment there is a pair of distal electrodes 500 ₁, a pair of middle electrodes 500 ₂, and a pair of proximate electrodes 500 ₃ on each side of the knife channel 516. The metallic outer portion or channel 22 of the end effector 12 or the metallic anvil 24 may serve as the counter-electrode (or cathode) for each of the three upper active electrodes (or anodes) 500. The upper electrodes 500 may be coupled to the RF source. When energized, RF energy may propagate between the upper electrodes 500 and the counter electrode, coagulating tissue clamped between the electrodes.

The electrodes 500 may be energized simultaneously or in various orders, such as sequentially. For embodiments where the electrodes 500 are energized according to a sequence, the sequence may be automatic (controlled, for example, by a controller (not shown) in communication with the RF source) or by selection by the user. For example, the proximate electrodes 500 ₃ could be energized first; then the middle electrodes 500 ₂; then the distal electrodes 500 ₁. That way, the operator (e.g., the operating surgeon) can selectively coagulate areas of the staple line. The electrodes in such an embodiment could be controlled by a multiplexer and/or a multiple output generator, as described further below. That way, the tissue under each electrode 500 could be treated individually according to the coagulation needs. Each electrode in the pair may be connected to the RF source so that they are energized at the same time. That is, for the distal pair of active electrodes 500 ₁, each, being on opposite sides of the knife channel, may be energized by the RF source at the same time. Same for the middle pair of electrodes 500 ₂ and the proximate pair of electrodes 500 ₃, although, in an embodiment where the electrode pairs are energized in sequence, the distal pair is not energized at the same time as the middle and proximate pairs, and so on.

Further, various electrical parameters, such as impedance, delivered power or energy, etc., could be monitored and the output to particular electrodes 500 could be modified to produce the most desirable tissue effect. Additionally, another advantage is in the case of a metal staple or other electrically conductive object left from a previous instrument firing or surgical procedure that may cause a short of the electrodes. Such a short situation could be detected by the generator and/or multiplexer, and the energy could be modulated in a manner appropriate for the short circuit.

In addition, energizing the electrodes 500 in sequence reduces the instantaneous power required from the RF source in comparison to a design that would has one set of electrodes as long as the combined length of the three segmented electrodes 500 shown in FIG. 23. For example, for electrode configurations as shown in the '312 Patent, it has been demonstrated that it would require fifty to one-hundred watts to coagulate successfully forty-five mm lines on either side of the cut line. By using smaller active electrodes (e.g., the upper electrodes 500) that have less surface area than the larger return electrodes (e.g., the metallic anvil 24), the smaller active electrodes 500 can concentrate the therapeutic energy at the tissue while the larger, return electrode is used to complete the circuit with minimal impact on the tissue interface. In addition, the return electrode preferably has greater mass and thereby is able to stay cooler during electrosurgical application.

The electrodes 500 may be surrounded by an electrically insulating material 504, which may comprise a ceramic material.

FIG. 24 shows another embodiment having segmented RF electrodes. In the embodiment shown in FIG. 24, there are four co-linear segmented electrodes 500 ₁₋₄ of equal length (15 mm in this example). Like the embodiment of FIG. 23, the electrodes 500 of FIG. 24 could be energized simultaneously or sequentially.

FIG. 25 shows yet another embodiment, in which the segmented electrodes have different lengths. In the illustrated embodiment, there are four co-linear segmented electrodes, but the most distal electrodes 500 ₁, 500 ₂ are 10 mm in length, and the two proximate electrodes 500 ₃, 500 ₄ are 20 mm in length. Having short distal electrodes may provide the advantage of concentrating the therapeutic energy, as mentioned above.

FIG. 59 shows an embodiment having fifteen pairs of segmented RF electrodes 500 on a circuit board 570, or other type of suitable substrate, on the lower surface of the anvil 24 (i.e., the surface facing the channel 22). The various electrode pairs are energized by the RF source (or generator) 574. The multiplexer 576 may distribute the RF energy to the various electrode pairs as desired under the control of a controller 578. According to various embodiments, the RF source 574, the multiplexer 576, and the controller 578 may be located in the handle 6 of the instrument.

In such an embodiment, the circuit board 570 may comprise multiple layers that provide electrical connections between the multiplexer 576 and the various electrode pairs. For example, as shown in FIGS. 60 to 63, the circuit board may comprise three layers 580 ₁₋₃, each layer 580 providing connections to five of the electrode pairs. For example, the upper most layer 580 ₃ may provide connections to the most proximate five electrode pairs, as shown in FIGS. 60 and 61; the middle layer 580 ₂ may provide connections to the middle five electrode pairs, as shown in FIGS. 60 and 62; and the lowest layer 580 ₁ may provide connections to the most distal five electrode pairs, as shown in FIGS. 60 and 63.

FIG. 64 shows a cross-sectional end view of the anvil 24 according to such an embodiment. The circuit board 570, adjacent to the staple pockets 584, comprises three conducting layers 580 ₁₋₃, having insulating layers 582 ₁₋₄ therebetween. FIGS. 65 and 66 show how the various layers 580 ₁₋₃ may be stacked to connect back to the multiplexer 576 in the handle.

An advantage of having so many RF electrodes in the end effector 12, as shown in FIG. 67, is that, in the case of a metal staple line 590 or other electrically conductive object left in the tissue 592 from a previous instrument firing or surgical procedure that may cause a short of the electrodes, such a short situation could be detected by the generator and multiplexer, and the energy could be modulated in a manner appropriate for the short circuit.

FIG. 27 shows another end effector 12 with RF electrodes. In this embodiment, the end effector 12 only comprises distal electrodes 500 ₁, with the metallic anvil 24 serving as the return electrode. The distal electrodes 500 ₁ do not span the entire length of the anvil 24, but only a fraction of the length. In the illustrated embodiment, distal electrodes 500 ₁ are only approximately 20 mm in length along a 60 mm anvil, so that the distal electrodes 500 ₁ only cover approximately the most distal ⅓ of the anvil length. In other embodiments, the distal electrodes 500 ₁ could cover the most distal 1/10 to ½ of the anvil length. Such embodiments could be used for spot coagulation, as described in U.S. Pat. No. 5,599,350, which is incorporated herein by reference.

FIG. 28 shows yet another embodiment of the end effector 12 with RF electrodes. In this embodiment, an active electrode 500 is positioned at the distal tip of the anvil 24, insulated by the anvil 24 by an electrically non-conductive insulator 504, which may be made of ceramic material. Such an embodiment may be used for spot coagulation.

FIGS. 29 to 32 illustrate other embodiments of the end effector 12 that may be useful for spot coagulation. In these embodiments, the anvil 24 comprises a pair of electrodes 500 ₁, 500 ₂ at the distal end of the anvil 24 and along a lateral side of the anvil 24. FIG. 29 is front-end view of the anvil 24 according to such an embodiment, FIG. 30 is a side view, FIG. 31 is an enlarged fragmentary front-end view, and FIG. 32 is a top view. In such an embodiment, the metallic anvil 24 may act as the return electrode. The active electrodes 500 ₁, 500 ₂ may be insulated from the anvil 24 by electrically non-conductive insulators 504, which may comprise ceramic material.

FIGS. 33 to 36 show an embodiment where the anvil 24 comprises two distal electrodes 500 ₁, 500 ₂ located at the top, center of the anvil 24. Again, the metallic anvil 24 may act as the return electrode, and the active electrodes 500 ₁, 500 ₂ may be insulated from the anvil 24 by electrically non-conductive insulators 504.

FIGS. 37 to 40 show an embodiment where one active electrode 500 ₁ (e.g., the active electrode) is positioned on the anvil 24, and another active electrode 500 ₂ is positioned on the lower jaw 22, and preferably on the cartridge 34. The metallic anvil 24 may serve as the return electrode. The anvil electrode 500 ₁ is insulated from the anvil 24 by an insulator 504. The electrode 500 ₂, being positioned in the cartridge 34, which is preferably made from a non-conductive material such as plastic, is insulated from the metallic channel 22 by the cartridge 34.

FIGS. 41 to 44 show an embodiment where the anvil 24 has two active electrodes 500 ₁, 500 ₂ at the very most distal end of the anvil 24 that extend completely from the upper surface of the anvil 24 to the lower surface. Again, the metallic anvil 24 may act as the return electrode, and the active electrodes 500 ₁, 500 ₂ may be insulated from the anvil 24 by electrically non-conductive insulators 504.

FIGS. 45 to 48 show an embodiment where the cartridge 34 has two active electrodes 500 ₁, 500 ₂ at the very most distal end of the staple cartridge 34. In such an embodiment, the metallic anvil 24 or the metallic channel 22 may act as the return electrode. In this illustrated embodiment, the electrodes 500 ₁, 500 ₂ are connected to insulator inserts 503, but in other embodiments, the insulator inserts 503 could be omitted and the plastic cartridge 34 may serve as the insulator for the electrodes 500 ₁, 500 ₂.

FIGS. 49 to 52 show an embodiment having one active electrode 500 ₁ at the very most distal end of the anvil 24 and another active electrode 500 ₂ at the very most distal end of the cartridge 34. Again, in such an embodiment, the metallic anvil 24 or the metallic channel 22 may act as the return electrode. In this illustrated embodiment, the electrode 500 ₂ is connected to insulator inserts 503, 505, but in other embodiments, the insulator inserts 503, 505 could be omitted and the plastic cartridge 34 may serve as the insulator for the electrode 500 ₂.

FIG. 57 is a side view and FIG. 58 is a cross-sectional side of the handle 6 according to other embodiments of the present invention. The illustrated embodiment only includes one trigger, the closure trigger 18. Activation of the knife, staple drivers, and/or RF electrodes in this embodiment may be achieved through means other than a separate firing trigger. For example, as shown in FIG. 57, actuation of the knife, staple drivers, and/or RF electrodes may be activated by a push-button switch 540 or other type of switch that is in a position that is convenient for the operator. In FIG. 57, the switch 540 is shown at the most proximate portion of the handle 6. In another embodiment, the switch may be positioned near the distal end of the handle 6 so that pulling of the nozzle 539 activates the switch to cause actuation of the instrument. In such an embodiment, a switch (not shown) may be placed under or near the nozzle 539 so that movement of the nozzles toggles the switch.

Alternatively, actuation of the knife, staple drivers, and/or RF electrodes may be activated by voice or other sound commands detected by a microphone 542. In other embodiments, the handle 6 may comprise a RF or sonic transceiver 541, which may receive and/or transmit RF or sonic signals to activate the instrument. Also, as shown in FIG. 58, a foot pedal or switch 544 could be used to active the instrument 10. The foot pedal 544 may be connected to the handle 6 by a cord 545. Also, the handle 6 may comprise a dial control 546 or some other suitable control device for controlling actuation of the segmented RF electrodes (see, for example, FIGS. 23 and 24). Using such a control device 546, the operator may serially activate the various pairs of RF electrodes 500 in the end effector 12.

The instrument 10 shown in FIGS. 57 and 58 also includes many feedback systems for the user. As mentioned above, the instrument 10 may comprise the speaker 543 for audibleizing commands or instructions to the operator. In addition, the handle 6 may comprise visual indicators 548, such as LEDs or other light sources that provide visual feedback regarding actuation of the various segmented RF electrodes. For example, each of the visual indicators 548 could correspond to one of the segmented RF electrode pairs. The corresponding visual indicator 548 may be activated when the segmented RF electrode pair is activated. In addition, the handle 6 may comprise an alphanumeric display 550, which may be an LED or LCD display, for example. The display 550 may be connected to a circuit board 552 inside the handle 6. The handle 6 may also comprise a vibrator 554 in the pistol grip portion 26 that may provide vibrational feedback to the operator. For example, the vibrator 554 could vibrate each time that one of the segmented pairs of the RF electrodes in the end effector 12 is activated.

FIG. 26 is a cross-sectional view of the end effector 12 according to various embodiments where the electrodes are on the upper jaw (or anvil) 24. In the illustrated embodiment, the active electrodes 500 are positioned adjacent the knife slot 516. The metal anvil 24 may serve as the return electrode. Insulators 504, which may be made of ceramic, insulate the electrodes 500 from the metallic anvil 24. The embodiment of FIG. 68 is similar to that of FIG. 26, except that electrodes 500 are made smaller, such that a portion of the insulators 504 can extend between the respective electrodes 500 and the edges of the knife channel 516.

FIG. 53 is a cross-sectional end view of the end effector 12 according to another embodiment. In this embodiment, like the embodiment of FIG. 26, the active electrodes 500 ₁, 500 ₂ are on the anvil 24 on opposite sides of the knife channel. The electrodes 500 ₁, 500 ₂ are insulated from the metallic anvil by insulators 504, which again preferably comprise ceramic material. In this embodiment, however, the insulators 504 are made very thin (compare with FIG. 26). Making the insulators 504 very thin provides the potential advantage that the anvil 24 may include a relatively large metal section 520 above the electrodes 500, thereby potentially supporting a slimmer anvil profile for a given anvil stiffness, or a stiffer profile for a given anvil cross-sectional dimension. The insulators 504 may be cast in or sputter coated onto the anvil 24.

FIG. 54 illustrates another embodiment. In this embodiment, the active electrodes 500 ₁, 500 ₂ are sputter coated or bonded to the insulators 504, which may also be sputter coated or bonded to the anvil 24. Like the embodiment of FIG. 53, this design allows for more anvil material above the electrodes. In such an embodiment, the electrodes 500 ₁, 500 ₂ may comprise silver, which is a good conductor of electricity and has antimicrobial properties.

FIG. 55 shows a side view of the end effector according to another embodiment. In this embodiment, a thin film of electrically insulating material 530 is deposited on the face of the cartridge 34. The insulating film 530 preferably comprises a heat- and arc-resistant material, such as ceramic. This would tend to increase the resistance of the cartridge 34 to arc-tracking and shorting, permitting more firings between changes of the cartridge 34. In addition, if the cartridge 34 was a poor electrical conductor, it would support quicker heating of tissue and reduce the overall energy requirements. The active electrodes (not shown in FIG. 55) may be in the anvil 24, as described in embodiments above.

FIG. 56 shows an embodiment that is similar to that shown in FIG. 55, except that in FIG. 56, a thin layer 532 of slightly electrically conductive material is deposited on top of the insulating film 530. The conductivity of the thin, slightly conductive layer 532 may be lower than the conductive of the tissue clamped in the end effector 12 for treatment. As such, the thin, slightly conductive layer 532 would provide a reduced-conductivity path to provide additional heating of the clamped tissue. This would tend to reduce the time required to heat the tissue and achieve coagulation.

As described above, the instrument 10 may comprise an articulation pivot 14 for articulating the end effector 12. A clinician or operator of the instrument 10 may articulate the end effector 12 relative to the shaft 8 by utilizing the articulation control 16, as described in more detail in published U.S. Patent Application Publication No. 2007/0158385, entitled SURGICAL INSTRUMENT HAVING AN ARTICULATING END EFFECTOR, now U.S. Pat. No. 7,670,334, which is incorporated herein by reference. In other embodiments, rather than a control device that is integrated with the instrument 10, the end effector 12 may be articulated by a separate instrument, such as gripper, that is inserted into the patient so that its operative portion is near the end effector 12 so that it can articulate the end effector 12 as desired. The separate instrument may be inserted through a different opening as the end effector 12, or through the same opening. Also, different operators can operate the separate instruments, or one person can operate both instruments, to articulate the end effector 12. In another passive articulation scenario, the end effector 12 may be articulated by carefully pushing it against other parts of the patient to achieve the desired articulation.

In another embodiment, the end effector 12 may be connected to the handle by a flexible cable. In such an embodiment, the end effector 12 could be positioned as desired and held in position by use of another instrument, e.g., a separate gripper instrument. In addition, in other embodiments, the end effector 12 could be positioned by a separate instrument and clamped by a second separate instrument. In addition, the end effector 12 could be made sufficiently small, such as 8 to 9 mm wide by 10 to 11 mm tall, so that a pull-to-close mechanism could be used to clamp the end effector from the handle 6. The pull-to-close mechanism could be adapted from that described in U.S. Pat. No. 5,562,701, entitled CABLE-ACTUATED JAW ASSEMBLY FOR SURGICAL INSTRUMENTS, which is incorporated herein by reference. The cable 600 could be disposed in or along a flexible endoscope for use, for example, in upper or lower gastro-intestinal tract procedures.

In yet another embodiment, as shown in FIGS. 69 and 70, the instrument 10 may comprise a flexible neck assembly 732 enabling articulation of the end effector 12. When an articulation transmission assembly 731 coupled to the shaft 8 is rotated, it may cause remote articulation of the flexible neck assembly 732. The flexible neck assembly 732 may comprise first and second flexible neck portions 733, 734, which receive first and second flexible band assemblies 735, 736. Upon rotation of the articulation transmission assembly 731, one of the first and second flexible transmission band assemblies 735, 736 is moved forwardly and the other band assembly is moved rearwardly. In response to the reciprocating movement of the band assemblies within the first and second flexible neck portions 733, 734 of the flexible neck assembly 732, the flexible neck assembly 732 bends to provide articulation. A further description of the flexible neck is described in U.S. Pat. No. 5,704,534, which is incorporated herein by reference.

The devices disclosed herein can be designed to be disposed of after a single use, or they can be designed to be used multiple times. In either case, however, the device can be reconditioned for reuse after at least one use. Reconditioning can include any combination of the steps of disassembly of the device, followed by cleaning or replacement of particular pieces, and subsequent reassembly. In particular, the device can be disassembled, and any number of the particular pieces or parts of the device can be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, the device can be reassembled for subsequent use either at a reconditioning facility, or by a surgical team immediately prior to a surgical procedure. Those skilled in the art will appreciate that reconditioning of a device can utilize a variety of techniques for disassembly, cleaning/replacement, and reassembly. Use of such techniques, and the resulting reconditioned device, are all within the scope of the present application.

Preferably, the various embodiments of the invention described herein will be processed before surgery. First, a new or used instrument is obtained and if necessary cleaned. The instrument can then be sterilized. In one sterilization technique, the instrument is placed in a closed and sealed container, such as a thermoformed plastic shell covered with a sheet of TYVEK (commercially available from E. I. du Pont de Nemours and Company). The container and instrument are then placed in a field of radiation that can penetrate the container, such as gamma radiation, x-rays, or high-energy electrons. The radiation kills bacteria on the instrument and in the container. The sterilized instrument can then be stored in the sterile container. The sealed container keeps the instrument sterile until it is opened in the medical facility.

It is preferred that the device is sterilized. This can be done by any number of ways known to those skilled in the art including beta or gamma radiation, ethylene oxide, steam and other methods.

While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications may readily appear to those skilled in the art. The various embodiments of the present invention represent vast improvements over prior staple methods that require the use of different sizes of staples in a single cartridge to achieve staples that have differing formed (final) heights.

Accordingly, the present invention has been discussed in terms of endoscopic procedures and apparatus. However, use herein of terms such as “endoscopic” should not be construed to limit the present invention to a surgical stapling and severing instrument for use only in conjunction with an endoscopic tube (i.e., trocar). On the contrary, it is believed that the present invention may find use in any procedure where access is limited, including but not limited to laparoscopic procedures, as well as open procedures. Moreover, the unique and novel aspects of the various staple cartridge embodiments of the present invention may find utility when used in connection with other forms of stapling apparatuses without departing from the spirit and scope of the present invention. 

What is claimed is:
 1. A surgical instrument, comprising: a channel jaw comprising a distal end; a replaceable cartridge body positioned in said channel jaw; staples removably stored in said replaceable cartridge body; a drive screw extending within said channel jaw; a cutting member operably coupled to said drive screw, wherein said cutting member comprises a knife edge configured to incise tissue, and wherein said drive screw is rotatable to drive said cutting member toward said distal end during a staple firing stroke; an anvil comprising forming pockets configured to deform said staples during said staple firing stroke; an elongate shaft; a rotatable shaft extending at least partially through said elongate shaft, wherein said rotatable shaft is configured to rotate said drive screw to perform said staple firing stroke; an electric motor configured to rotate said rotatable shaft; and a control system configured to limit the torque supplied by said electric motor to limit the actuation force of said cutting member, wherein said control system is further configured to control the speed of said electric motor.
 2. The surgical instrument of claim 1, wherein said cutting member comprises a first cam configured to engage said channel jaw and a second cam configured to engage said anvil during said staple firing stroke.
 3. A surgical instrument assembly, comprising: a channel jaw comprising a distal end; a cartridge positioned in said channel jaw; staples removably stored in said cartridge; a drive screw extending within said channel jaw; a firing member drivable by said drive screw, wherein said firing member comprises a knife edge configured to incise tissue, and wherein said drive screw is rotatable to drive said firing member toward said distal end during a staple firing stroke; an anvil configured to deform said staples during said staple firing stroke; an elongate shaft; a rotatable shaft extending at least partially through said elongate shaft, wherein said rotatable shaft is operably coupled to said drive screw; an electric motor configured to rotate said rotatable shaft; and a control system configured to control the torque supplied by said electric motor to control the actuation force of said firing member, wherein said control system is further configured to control the speed of said electric motor.
 4. The surgical instrument assembly of claim 3, wherein said firing member comprises a first portion configured to engage said channel jaw and a second portion configured to engage said anvil during said staple firing stroke to control the position of said channel jaw and said anvil relative to one another.
 5. The surgical instrument assembly of claim 3, wherein said cartridge is replaceable with another cartridge after said staple firing stroke.
 6. A surgical instrument assembly, comprising: a cartridge jaw comprising a distal end; a cartridge positioned in said cartridge jaw; staples removably stored in said cartridge; a drive screw extending within said cartridge jaw; a firing member operably engaged with said drive screw, wherein said firing member comprises a knife edge configured to incise tissue, and wherein said drive screw is rotatable to drive said firing member toward said distal end during a staple firing stroke; an anvil jaw, wherein said staples are deformed against said anvil jaw during said staple firing stroke; an electric motor configured to rotate said drive screw; and a control system configured to limit the torque supplied by said electric motor to limit the force of said firing member and configured to control the speed of said electric motor.
 7. The surgical instrument assembly of claim 6, wherein said firing member comprises a first portion configured to engage said cartridge jaw and a second portion configured to engage said anvil jaw during said staple firing stroke to control the position of said cartridge jaw and said anvil jaw relative to one another.
 8. The surgical instrument assembly of claim 6, wherein said cartridge is replaceable with another cartridge after said staple firing stroke. 